A novel trust management framework for multi-cloud environments based on trust service providers

In this paper, we address the problem of trust management in multi-cloud environments based on a set of distributed Trust Service Providers (TSPs). These are independent third-party providers/trust agents, trusted by Cloud Providers (CPs), Cloud Service Providers (CSPs) and Cloud Service Users (CSUs), that provide trust related services to cloud participants. TSPs are distributed over the clouds, and they elicit raw trust evidence from different sources and in different formats. This evidence is information regarding the adherence of a CSP to a Service Level Agreement (SLA) for a cloud-based service and the feedback sent by CSUs. Using this information, they evaluate an objective trust and a subjective trust of CSPs. TSPs communicate among themselves through a trust propagation network that permits a TSP to obtain trust information about a CSP from other TSPs. Experiments show that our proposed framework is effective and relatively stable in differentiating trustworthy and untrustworthy CSPs in a multi-cloud environment.